Camera, aperture controlling method and apparatus, lens controlling method and apparatus, and edging amount controlling method and apparatus

ABSTRACT

Maximum and minimum aperture sizes are regulated with regard to a diaphragm in order to secure predetermined optical capability in an optical unit which includes a taking lens and the diaphragm. In a normal taking, the diaphragm is used within a normal taking range from the maximum to the minimum aperture sizes. In the present invention, an aperture size which is larger than the maximum size and a size which is smaller than the minimum size (extra aperture size or extra small size) are respectively set at outside the range that secures the capability. The aperture sizes of the diaphragm at outside the specified range are used at least for one of the following: automatic exposure (AE) adjustment, auto focus (AF) adjustment, electronic zoom, displaying a moving image, taking for recording the moving image, and taking under a low resolution by thinning out pixels.

This application is a Divisional of application Ser. No. 09/873,311filed on Jun. 5, 2001 now U.S. Pat. No. 7,292,280, and for whichpriority is claimed under 35 U.S.C. §120; and this application claimspriority of Application Nos. 2000-167566 and 2001-144339, filed in Japanon Jun. 5, 2000 and May 15, 2001, respectively under 35 U.S.C. §119; theentire contents of all are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a camera such as a digital camera, avideo camera and a silver-halide camera, an aperture controlling method,an aperture controlling apparatus, a lens controlling method, a lenscontrolling apparatus, an edging amount controlling method and an edgingamount controlling apparatus which are applied to an optical system ofthe camera.

2. Description of the Related Art

In a conventional art, an operatable range of a lens is restricted withregard to a diaphragm for a camera, a point-blank limit, and a zoomlimit, in order to secure a predetermined optical capability (e.g. animaging capability) of the lens. Concerning the diaphragm for example, amaximum and a minimum aperture sizes are so specified as to control thediaphragm within the operatable range. Japanese Patent ApplicationLaid-open No. 5-53170 discloses changing a diaphragm corresponding witha zoom position and correcting a variance of the diaphragm due tozooming. A diaphragm adjusting system using a solid-state imaging deviceilluminates an auxiliary light if a subject is too dark, and also raisesoutputting power by gaining an output from the imaging device (called“gain-up”), thereby gaining a signal level.

However, in an automatic exposure adjustment (AE), because noisecompositions are amplified by gaining up and performing photometry ifthe brightness of the subject is too low, many errors occur, andphotometry capability at a low brightness is poor. Similarly, with anauto focusing adjustment in which a portion having the most of highfrequency compositions of a video signal is a focus position, focusingcapability is lowered because the noise compositions are amplified ifthe output signal of the imaging signal is amplified.

Other problems concerning the conventional camera are that: the cameraeasily vibrates when using an electronic zoom, an image quality of amovie display for confirming a view angle is deteriorated with respectto the subject with a low brightness, observability of the movie displayis poor due to a smear phenomenon which occurs in taking of the subjectwith extreme brightness, and so forth.

SUMMARY OF THE INVENTION

The present invention has been developed in view of the above-describedcircumstances, and has as its object the provision of a method andapparatus for controlling a diaphragm of camera and camera whichachieves improvement of capability as a camera, by suitably using adiaphragm which is larger than a maximum diaphragm for a normal takingand a diaphragm which is smaller than a minimum diaphragm for a normaltaking corresponding with a use.

Moreover, the present invention provides a technique for improving andexpanding the capability of the camera by proving a wider interlockingrange than a normal taking range, with regard not only to the diaphragmbut also to a zoom range (operatable range of a focal length) and afocus adjustment range, and using the lens at outside the range whichsecures its capability corresponding with a taking condition and aspecial use.

In order to achieve the above-described objects, the present inventionis directed to a method for controlling an aperture of a camera,comprising the steps of: determining an aperture out of an aperturerange for a normal shooting which secures predetermined opticalcapability; and controlling a diaphragm mechanism to use the aperturefor at least one of the following: automatic exposure, auto focus,electronic zoom, real-time displaying of a moving image, recording of amoving image, and recording an image with a low resolution due toreduced pixels.

According to the present invention, a maximum and a minimum aperturesizes are so specified as to secure predetermined optical capability ofthe lens, and in a normal taking, an aperture size within a focus rangeof a normal taking from the maximum to the minimum aperture sizes isused. In the present invention, an aperture size at outside thespecified range (extra aperture size) which has a larger size than themaximum size, or an aperture size at outside the specified range (extrasmall size) which has a smaller aperture size than the minimum aperturesize, or both of the extra aperture size and extra small size areprovided to the diaphragm mechanism. The focus positions are used whenactivating at least one of the following: automatic exposure, autofocus, electronic zoom, movie display, taking for recording a movingimage, and taking under a low resolution by thinning out pixels.

Therefore, the capability of the lens can be fully used withoutdeteriorating the taken image, and the respective capability of thecamera can be improved.

In order to achieve the above-described objects, the present inventionis directed to an apparatus for controlling an aperture of a camera,comprising: a first determining device that determines an aperture rangefor a normal shooting which secures predetermined optical capability; asecond determining device that determines an aperture range including anaperture out of the aperture range for the normal shooting; and acontrolling device that controls a diaphragm mechanism to set anaperture within the aperture range determined by the second determiningdevice for at least one of automatic exposure and auto focus, andcontrols the diaphragm mechanism to set an aperture within the aperturerange determined by the first determining device for recording of animage.

In order to achieve the above-described objects, the present inventionis directed to an apparatus for controlling an aperture of a camera,comprising: a first determining device that determines an aperture rangefor a normal shooting which secures predetermined optical capability; asecond determining device that determines an aperture range including anaperture out of the aperture range for the normal shooting; and acontrolling device that controls a diaphragm mechanism to set anaperture within the aperture range determined by the second determiningdevice for a shooting with electronic zoom, and controls the diaphragmmechanism to set an aperture within the aperture range determined by thefirst determining device for a shooting without the electronic zoom.

In order to achieve the above-described objects, the present inventionis directed to an apparatus for controlling an aperture of a camera,comprising: a first determining device that determines an aperture rangefor a normal shooting which secures predetermined optical capability; asecond determining device that determines an aperture range including anaperture out of the aperture range for the normal shooting; and acontrolling device that controls a diaphragm mechanism to set anaperture within the aperture range determined by the first determiningdevice for recording of a still image, and controls the diaphragmmechanism to set an aperture within the aperture range determined by thesecond determining device for at least one of real-time displaying of amoving image and recording of a moving image.

In order to achieve the above-described objects, the present inventionis directed to an apparatus for controlling an aperture of a camera,comprising: a first determining device that determines an aperture rangefor a normal shooting which secures predetermined optical capability; asecond determining device that determines an aperture range including anaperture out of the aperture range for the normal shooting; and acontrolling device that controls a diaphragm mechanism to set anaperture within the aperture range determined by the first determiningdevice for a shooting in a high-resolution mode with a large number ofpixels, and controls the diaphragm mechanism to set an aperture withinthe aperture range determined by the second determining device for ashooting in a low-resolution mode with a small number of pixels.

Another embodiment is presented below for using the lens at outside therange for securing the capability (an interlocking range which is widerthan the normal taking range) corresponding with a taking condition.

Although the image quality around the screen is poorer as the diaphragmreaches to the aperture side, the subject often exists at the center ofthe screen at the time of a strobe taking, and the area around thescreen is low with brightness; hence, the taken image is with asatisfactory quality even though the image quality is slightly poor dueto low brightness at the periphery. In view of the fact, the extraaperture size is used at a time of the strobe taking in order to obtaina strobe reaching length.

In order to achieve the above-described objects, the present inventionis directed to a camera, comprising: a diaphragm mechanism that adjustsan amount of light entering the camera through a taking lens; anelectronic flash that emits auxiliary light to a subject at an exposure;a first determining device that determines an aperture range for anormal shooting without the electronic flash; and a second determiningdevice that determines an aperture range for an electronic flashshooting with the electronic flash.

In this case, if the camera further comprises a photometry device,whether to use the extra aperture is preferably determined according tothe measured subject distance. In other words, the camera takes thesubject with the aperture size if a distance to the subject is a rangein which the strobe can reach by the aperture size within the range forsecuring the capability, and takes with the extra aperture size if thedistance to the subject is more than the range. In order to achieve theabove-described objects, the present invention is directed to the camerafurther comprising: a pre-emitting device that illuminating the subjectby emitting light before the exposure; a photometry device that performsphotometry for each area of a divided taking screen when thepre-emitting device emits the light; and a determining device thatdetermines whether to use the second determining device according to aresult of the photometry by the photometry device. The extra aperturesize is preferably used at the strobe taking only in a case the subjectexisting at the center of the screen is confirmed as a result of thedividing photometry by illuminating the subject with the pre-emittingmeans.

In order to achieve the above-described objects, the present inventionis directed to the camera further comprising: an attaching part for awide conversion lens; and a detecting device for detecting attachment ofthe wide conversion lens to the attaching part, wherein the camera usesthe second determining device when the wide conversion lens is attachedto the attaching part.

In a case where the wide conversion lens is attached to a lens barrel ofthe camera, the image is not problematic in a practical use even thoughthe image quality at the periphery is poor because the strobe does notreach to the periphery due to its illuminating characteristics.Therefore, in one embodiment, the aperture size of the diaphragm whichis outside the range that secures the capability (extra aperture size)is used when attaching the wide conversion lens.

In order to achieve the above-described objects, the present inventionis directed to a camera, comprising: a taking lens; a diaphragmmechanism that adjusts an amount of light entering the camera through ataking lens; a first determining device that determines an aperturerange for a normal shooting which secures predetermined opticalcapability; a second determining device that determines an aperturerange including an aperture out of the aperture range for the normalshooting; a shooting mode setting device that sets a shooting mode; anda controlling device that controls the diaphragm mechanism to set anaperture within the aperture range according to the shooting modeselected by the shooting mode setting device.

For example, the second determining device is used when a portrait modeis selected.

Among types of taking modes for automatically setting a suitable takingcondition corresponding with a taking scene, a portrait mode issatisfactory if the periphery of the image is blurred and thus thesubject at the center stands out clearly. Thus, the image in theportrait mode is not problematic even though the image quality of theperiphery is poor, and the aperture size of the diaphragm at outside therange for securing the capability is used.

In order to achieve the above-described objects, the present inventionis directed to a camera, comprising: a taking lens that forms a subjectimage on an imaging surface; a taking lens controlling device thatadjusts a position of the taking lens; a resolution changing device thatchanges a resolution of an image; a first determining device thatdetermines an area of the taking lens for a shooting with a highresolution; and a second determining device that determines an area ofthe taking lens for a shooting with a low resolution.

In order to achieve the above-described objects, the present inventionis directed to a camera, comprising: a taking lens; an imaging devicethat changes an optical image of a subject which enters the camerathrough the taking lens into electric signals; an electronic zoomingdevice that obtains an enlarged image by electronically processing imagesignals obtained through the imaging device; a taking lens controllingdevice that adjusts a position of the taking lens; a first determiningdevice that determines a range of the taking lens for a normal shootingwithout the electronic zooming device; and a second determining devicethat determines a range of the taking lens for an electronic zoomingwith the electronic zooming device.

A macro area of a focus position which is adjustable by focusing isnormally regulated because a resolution of the entire image and aresolution of the periphery of the image and distortion are large.However, a taken image is not affected at a time of taking under a lowresolution, or at a time of an electronic zoom (enlarging process of animage by processing an image signal); hence a taking is possible at evena shorter distance than the regulated range (focus point-blank limit).

In order to achieve the above-described objects, the present inventionis directed to a camera, comprising: a taking lens; an imaging devicethat changes an optical image of a subject which enters the camerathrough the taking lens into electric signals; a focal lengthcontrolling device that adjusts a focal length of the taking lens; aresolution changing device that changes a resolution of an image; afirst determining device that determines a focal-length area of thetaking lens for a shooting with a high resolution; and a seconddetermining device that determines a focal-length area of the takinglens for a shooting with a low resolution.

In order to achieve the above-described objects, the present inventionis directed to a camera, comprising: a taking lens; an imaging devicethat changes an optical image of a subject which enters the camerathrough the taking lens into electric signals; an electronic zoomingdevice that obtains an enlarged image by electronically processing imagesignals obtained through the imaging device; a focal length controllingdevice that adjusts a focal length of the taking lens; a firstdetermining device that determines a focal-length area of the takinglens for a normal shooting without the electronic zooming device; and asecond determining device that determines a focal-length area of thetaking lens for an electronic zooming shooting with the electroniczooming device.

With a zoom lens, an optical telephoto end is often regulated by lenscapability, but the image is not affected if taken in the low resolutionmode or in the electronic zoom; thus a taking at a position closer tothe optical telephoto side than a taking by changing a normal focallength is possible.

In order to achieve the above-described objects, the present inventionis directed to a camera, comprising: a taking lens; a diaphragmmechanism that adjusts an amount of light entering the camera throughthe taking lens; a vibration amount determining device that determinesan amount of vibration of the camera; a storing device that storesoptical data related to the taking lens; and a controlling device thatcompares the amount of vibration determined by the vibration amountdetermining device with the optical data, and changes an apertureaccording to a result of comparison.

If the focal length of the taking lens is at the telephoto side,vibrations, for example by hands, easily occurs. However, if an image istaken in the low resolution mode, such vibrations are not obvious.Therefore, an amount of blur in the image caused by the vibrations iscalculated and the result of the calculation is compared with the imagequality data in an extra aperture. If the amount of blur by vibrationsis larger than the image quality data in the extra aperture, the shutterspeed is accelerated by using the extra aperture size so as to take theimage at a point where the vibrations and the image quality arebalanced.

A contour intensity is preferably controlled so that lowering of theresolution due to a lowered image quality of the optical system issupplemented and that an edging is stricter with respect to the imagesignal.

In order to achieve the above-described objects, the present inventionis directed to a method for controlling an edging, wherein: a cameracomprises an imaging device that changes an optical image of a subjectwhich enters the camera through a taking lens into electric signals, andan edging device that performs the edging for an image obtained by theimaging device; and a control amount for deciding a degree of the edgingthe edging device is changed in response to one of the followingconditions: an aperture, a position of the taking lens, and a focallength of the taking lens. The edging can be controlled by changing acircuit gain of the edging circuit or changing a coring level.

In order to achieve the above-described objects, the present inventionis directed to a solid-state imaging device in which a large number ofphotoelectric converting devices are arranged and a micro lens isarranged at a front part of each of the photoelectric convertingdevices, wherein an aperture rate of each micro lens is changed inaccordance with a position of the micro lens. This prevents a decreaseof the image quality at the periphery of the display.

The aperture rate is preferably smaller toward periphery of a lightreceiving surface of the solid-state imaging device. Among the microlenses arranged at the solid-state imaging device, the aperture rate ofthe micro lens which is arranged at the peripheral portion is smallerthan that of the micro lens which is arranged at the central portion,whereby the decrease of the image quality at the periphery of thedisplay can be prohibited.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature of this invention, as well as other objects and advantagesthereof, will be explained in the following with reference to theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures and wherein:

FIG. 1 is a front perspective view of a camera in an embodiment of thepresent invention;

FIG. 2 is a rear perspective view of the camera in FIG. 1;

FIG. 3 is a block diagram of the camera in the embodiment of the presentinvention;

FIG. 4 is a graph showing changes in MTF by a diaphragm;

FIG. 5 is a graph showing enlarging of a focus area which can securecapability when using an electronic zoom;

FIG. 6 is a graph showing enlarging of the focus area which can be usedin a thinning out mode;

FIG. 7 is an explanatory view of a relationship between a view angle anda detected area at a time of an AF;

FIG. 8 is a flowchart showing a procedure for controlling the camera ina first embodiment;

FIG. 9 is an explanatory view of a relationship between the view angleand an area which is detected by an AE dividing and photometry;

FIG. 10 is a flowchart showing a procedure for controlling the camera ina second embodiment;

FIG. 11 is an explanatory view of a relationship between a normal viewangle and a taking angle when using an electronic zoom;

FIG. 12 is a flowchart showing a procedure for controlling the camera ina third embodiment;

FIG. 13 is a flowchart showing a procedure for controlling the camera ina fourth embodiment;

FIG. 14 is a flowchart showing a procedure for controlling the camera ina fifth embodiment;

FIG. 15 is a flowchart showing a procedure for controlling the camera ina sixth embodiment;

FIG. 16 is a front perspective view of the camera in another embodimentof the present invention;

FIG. 17 is a rear perspective view of the camera in another embodimentof the present invention;

FIG. 18 is a block diagram of the camera in FIG. 16;

FIG. 19 is a schematic view of dividing photometry;

FIG. 20 is a block diagram of the camera in still another embodiment ofthe present invention;

FIG. 21 is a graph showing a relationship (in a taking under a lowresolution) between a focus position and the MTF;

FIG. 22 is a graph showing a relationship (in the electronic zoom)between the focus position and the MTF;

FIG. 23 is a graph showing a relationship (in the taking under a lowresolution) between a focal length and the MTF;

FIG. 24 is a graph showing the relationship (in the electronic zoom)between the focal length and the MTF;

FIG. 25 is a schematic view showing a zoom range by a combination of anoptical zoom and an electronic zoom;

FIG. 26 is a block diagram showing an example of the contour intensitycircuit; and

FIG. 27 is a section view of a solid-state imaging device in theembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereunder preferred embodiments for a method and apparatus forcontrolling a diaphragm of a camera will be described in detailaccording to the accompanied drawings.

FIG. 1 is a perspective view at the front of the camera in an embodimentof the present invention. As seen from FIG. 1, a camera 10 has a takinglens 12 at substantially the center of its front, and a solid-stateimaging device (in FIG. 3 a reference number 28 is assigned to thesolid-state imaging device) such as a CCD image sensor is disposed atthe rear of the taking lens 12. A strobe emitting part 14 and a finderobject aperture 16 are provided to the front face of the camera 10, anda release switch 18 is provided on the ceiling (top face) of the camera10.

FIG. 2 is a rear perspective view of the camera 10. An optical finder 20and a liquid crystal monitor 22 are provided to the rear face of thecamera 10. A photographer decides a taking angle (composition of a view)while looking at a video image (a real time image for confirming a viewangle) which is displayed on the optical finder 20 or the liquid crystalmonitor 22, and performs taking.

FIG. 3 is a block diagram showing a structure of the camera 10. An irisdiaphragm 26 is disposed within an optical unit 24 which includes thetaking lens 12, and a solid-state imaging device 28 is disposed at therear of the optical unit 24. The iris diaphragm 26 is operated via adiaphragm control circuit 30, which is controlled by a control CPU 32.

An amount of light going through the taking lens 12 is adjusted by theiris diaphragm 26, and the light enters into the solid-state imagingdevice 28. Photo sensors are arranged in serial on a plane, and thesubject image formed on a light receiving surface of the solid-stateimaging device 28 is converted by each of the photo sensors into signalcharge in an amount corresponding with an amount of entered light. Thesignal charge thus accumulated is sequentially read out as a voltagesignal corresponding with the signal charge, by pulses supplied from theimaging device operating circuit, which is not shown.

The solid-state imaging device 28 has so-called an electronic shutterfunction which controls a charge accumulation time (i.e. shutter speed)of each of the photo sensors by a shutter gate pulse. Exposure iscontrolled by the combination of the iris diaphragm 26 and theelectronic shutter of the solid-state imaging device 28. The imagesignal outputted from the solid-state imaging device 28 is processed inan imaging circuit 34, which includes circuits such as a colorseparation circuit, a gain switch circuit, a γ(gamma) process circuit,and an A/D converting circuit.

The signal which is converted from an analog form to a digital form inthe imaging circuit 34 is stored in a memory 36 and an AE/AF detectingblock 38. The image signal having stored once in the memory 36 istransmitted to the AE/AF detecting block 38 which detects a level of theinputted image signal and brightness data of the subject is obtained. Aband pass filter is also provided to an AF detecting and processing partof the AE/AF detecting block 38, and a focusing condition of the subjectis detected by extracting high frequency composition of the videosignal. The AE/AF detecting block 38 in the present embodiment processesthe digital signal, but the video signal may also be detected in ananalog signal.

The data stored in the memory 36 is transmitted to a signal processingpart 42 via a bus 40. The signal processing part 42 is an image signalprocessing means which includes a brightness and color difference signalproducing circuit, a sharpness correcting (contour correcting) circuit,a white balance correcting circuit, a compression-expansion circuit, andso forth, and processes the image signal in accordance with a commandfrom the CPU 32. The image data inputted into the signal processing part42 is converted into a brightness signal (Y signal) and a colordifference signal (Cr and Cb signals) while going through apredetermined processes such as the gamma correction, and then stored inthe memory 36.

The image data stored in the memory 36 is read out in accordance withthe command of the CPU 32 and is converted into a signal in apredetermined display format (e.g. a color composition video signal ofan NTSC format), then is outputted to an image display device 44 such asthe liquid crystal monitor 22. The image display device 44 is notlimited to the liquid crystal monitor 22 which is built in the camera10, but may be an output terminal (not shown), or a liquid crystaldisplay or a CRT which is connected through a wired or a radiocommunication interface and the like.

The data in the memory 36 is periodically updated by the image signaloutputted from the solid-state imaging device 28, and the video signalproduced from the image data is supplied to the image display device 44;whereby an image captured by the solid-state imaging device 28 isdisplayed on the image display device as a moving image at a real time,or as a series of images even though not in the real time.

A signal for instructing start of recording is produced by pressing downthe release switch 18 which is included in an operation part 46, andtaking of the image data to be recorded is started in response toreceiving of the instruction signal. By the taking operation in responseto pressing down the release switch 18, the data taken in the memory 36goes through predetermined processes such as compressing and expandingand is recorded in an external storage device 48.

A memory card such as a smart media (Solid-State Floppy Disk Card) isused for the external storage device 48. Record medium is not limitedonly to the smart media, but may be a PC card, a compact flash, amagnetic disk, an optical disk, an optical magnetic disk, a memorystick, and so forth, and also a variety of types of media may be usedwhich is readable and recordable in accordance with an electronic, amagnetic, or an optical format, or combinations of them. In such use, asignal processing means and an interface corresponding with a medium tobe used is applied. Moreover, plural media may be attachable to thecamera 10 regardless of types of record media. A means for storing theimage data is not limited to a movable media which is detachable fromthe camera, but may be a record media (an inner memory) which is builtin the camera. When storing the image in the inner memory, acommunication interface is provided for transferring the data toexternal equipment such as a personal computer.

In a reproduction mode, the image data read out from the externalstorage device 48 is expanded by the compression-expansion circuit andis outputted to the image display device 44.

The CPU 32 is a control part which controls the respective circuits ofthe present camera system and is provided with a storage means such as aROM and a RAM (not shown). ROM stores a program to be processed by theCPU 32 and types of data required for controlling the circuits, whereasthe RAM is used for the CPU 32 as an operating area for performingrespective calculations. The CPU 32 controls operations of acorresponding circuit in accordance with an input signal received fromthe operating part 46, and at the same time controls display of theimage display device 44, an AF, and AE.

The operating part 46 is a block which includes an instruction inputmeans such as the release switch 18, a mode selection dial, an up/downkey, and a left/right key. The operating part 46 is not limited to apressing switch, a dial, a lever switch, and a slide switch; a desireditems may be selected from a setting menu and a selecting itemsdisplayed on a screen of the image display device 44 by using a cursor,a pointer, a touch panel, and the like on the screen. The operating part46 includes a means for designating a number of image pixels at a timeof image recording, a means for switching ON/OFF of the electronic zoomfunction, a means for operating a magnification of the electronic zoom,and so forth. The operating part 46 may be provided to the camera, or apart or the entire operating part 46 may be separated from the camera asa remote control transmitter.

The CPU 32 performs the respective calculations such as AF evaluationand AE calculation based on the data from the AE/AF detecting block 38,and controls the lens control circuit 50 so as to move the taking lens12 at a focusing position while controlling the diaphragm controlcircuit 30 to set an appropriate focus and at the same time controllingthe charge accumulation time of the solid-state imaging device 28.

The iris diaphragm 26 in the camera 10 of the present embodiment can bechanged between F1.4-F11, but a range for securing the capability tosatisfy a predetermined optical capability is between F2.8-F8. Ingeneral, an image quality at the periphery of the image is lowered ifthe diaphragm is opened large, and the image is blurred, which isundesirable. Thus, when taking the image to be recorded, a taking isexecuted in accordance with a program line which uses the range F2.8-F8(a normal taking range) which satisfies the predetermined opticalcapability.

Although the image quality at the periphery is lowered if the diaphragmis opened, the image quality at the center is almost unaffected.Therefore, respective capability of the camera can be achieved bychanging the diaphragm control under each of the conditions describedbelow. In other words, the lens capability is generally the best at thecenter of the screen and is lowered toward the periphery. The capabilityis also changed by the diaphragm. FIG. 4 is a graph showing changes ofan MTF (Modulation Transfer Function) of the lens by the diaphragm. InFIG. 4, a solid-lined graph shows the MTF changes at the center of thescreen while a graph with a dotted line shows the MTF changes at theperiphery of the screen.

As shown in FIG. 4, lowering of the capability is observed at bothaperture side and the small size side. Assuming that the MTF which cansecure the capability is 35%, a camera is designed to have a portion inwhich the MTF capability satisfies 35% of the entire area of the screenincluding the periphery is “a normal taking diaphragm range”. However,the MTF (the solid-lined graph) at the center of the screen has a partwhich achieves a better capability (a part which is higher than 35%)than the normal taking focus range with respect to the aperture side andthe small size side. The camera 10 in the present embodiment uses theaperture size which is outside the normal taking focus range since AEdetection is not affected even though the MTF is lowered.

If only a portion up to the center of the lens is used in a case of theelectronic zoom, the focus range which can be used (a range in which theMTF satisfies 35%) is wider than the normal taking focus range as seenfrom FIG. 5. Although not shown in the drawings, the portion of the MTFgraph between the center and the periphery resides in between thesolid-lined graph and the dotted line graph; thus the focus range whichsecures the capability changes corresponding with the zoom magnificationof the electronic zoom.

In a case of taking an image by thinning out the pixels in accordancewith a constant thinning out ratio rather than with a recording mode forrecording all the pixels of the solid-state imaging device 28, theacceptable MTF is lowered from the lens side. Thus as seen from FIG. 6,a focus range which is wider than a normal taking range (a focus rangefor the thinning-out mode taking) can be used at a time of thethinning-out mode taking. Outputs from the solid-state imaging device 28are thinned out not only for the thinning-out taking but also fordisplaying the moving image; hence the aperture size of the diaphragm atthe aperture side and the aperture size at the small size side which areoutside the normal taking focus range can be used in the same mannerdescribed above.

If the subject is too dark and so the moving image is dark, the movingimage can be displayed bright by using the aperture size which is closerto the aperture side than the normal taking focus range. In contrast, ifthe subject is so bright that smears easily occur, the quality as wellas observability of the moving image can be improved by using theaperture size which is closer to the small aperture size than the normaltaking focus range.

To be described in more detail, the present invention improves therespective capability of the camera by controlling the diaphragm withregard to the situations presented in embodiments 1 through 6, which maybe combined if necessary.

Embodiment 1 Extra Aperture Size at a Time of AF

The auto focus adjustment (AF) of the electronic camera is usuallycontrolled to make the point where the high frequency compositions ofthe video signal from the imaging device reach at the maximum point asthe focus point. When taking a moving image, the taken image is darkunder low brightness; hence, a subject under low brightness to someextent does not have problems without a precise focus.

With the still camera, on the other hand, a flashing device such as astrobe is used which emits light in synchronism with an exposureoperation at a time of recording so that a bright image can bephotographed. In the AF, however, the flashing device does not emitlight besides the precise focus cannot be obtained. If the flashingdevice emits light, the time for emitting light is shorter than the timerequired for the AF process, and the precise focus is not yet obtained.Concerning the above-described problems, the conventional art achievedthe AF by illuminating auxiliary light at the time of the AF, or byincreasing the gains of outputs from the solid-state imaging device soas to amplify the signal.

However, the auxiliary light requires a light source other than theoriginal light source which is exclusively used for the auxiliary light,and its electricity consumption is considerably large. Since a methodfor amplifying the signal from the solid-state imaging device by againing means also amplifies noise compositions, focusing capability ispoor.

In view of the above, the camera 10 of the present embodiment isprovided with a focus position having an extra large aperture size,which is not used for photographing (“the extra aperture size”, whichmeans a focus position that is outside the specified range). The camerais so controlled as to increase an amount of light to the solid-stateimaging device 28 by using the extra aperture size under low brightness,whereby the noise compositions can be suppressed while the AF capabilityunder low brightness can be improved.

FIG. 7 shows a relationship between the view angle and a detected areaat a time of the AF. As seen from FIG. 7, only an area (an AF detectarea 62) is used which is one quarter of the center of the screen withrespect to a view angle 60 at a time of taking (hereunder called a viewangle 60 at taking) at a time of the AF; hence an image is satisfactoryif the image quality is secured by the AF detect area 62.

Therefore, light in an amount that is four times as the normal takingcan be provided and at the same time the capability at the lowbrightness side can be improved by four times, by capturing the image inthe AF process with the aperture size (e.g. F1.4) which provides morebrightness than the aperture size (F2.8) which is used for the viewangle 60 at taking.

FIG. 8 shows a control flowchart for executing the above-describedprocess. When the camera control starts (Step S100) and the releaseswitch 18 is half-pressed, the AF process starts, and photometry for thesubject brightness is performed in order to measure the brightness ofthe subject (Step S110). Then, the subject brightness which is obtainedby the photometry and a specified value are compared (Step S112). If anormal aperture size is used when the subject brightness is lower thanthe specified value, the AF is determined to operate abnormally due to asmall output of the solid-state imaging device 28, and the process isseparated to Step S114.

At Step S114, an aperture size of diaphragm is selected which isdetermined to obtain the video signal most properly in the focus range(F1.4 or more and less than F2.8) which is closer to the aperture sidethan the normal diaphragm operation range, and the AF process isexecuted with the aperture size of the diaphragm.

At Step S112, on the other hand, the AF is determined to operatenormally within the normal diaphragm operation range if the subjectbrightness is larger than the specified value, and the process goes onto Step S116. At Step S116, an appropriate aperture size is selectedwithin the normal diaphragm operation range, that is, between F2.8-F8,and the AF process is executed by the focus value.

After the AF process is performed at Step S114 or Step S116, the processgoes on to Step S118. At Step S118, an aperture size for a normal taking(taking for recording) is calculated from a photometry value obtained atthe photometry for the subject brightness and a predetermined programline, and the aperture size is set in accordance with a result of thecalculation. At that time, the aperture size within the normal diaphragmoperation range (F2.8-F8) is selected.

Then, an exposure operation is performed when the release switch 18 isfully pressed (Step S120). The image data obtained at the exposureoperation is stored in the external storage device 48 after goingthrough required signal processes (Step S122), and the control sequenceis completed (Step S124).

In the present embodiment, an electronic still camera is mentioned asone example, however, cameras such as a silver-halide camera whichrecords an optical image in photosensitive material such as aphotographic film can be used if it applies an AF method of TTL and thesame result can be obtained.

Embodiment 2 Extra Aperture Size at a Time of AE

The automatic exposure control (AE) of the electronic camera iscontrolled in which a level of a video signal from the imaging device isintegrated in a predetermined area so that an average brightness valueis a proper level. In the conventional art, an exposure under lowbrightness is calculated by increasing an output gain from the imagingdevice so as to amplify the signal if the subject is too dark; but themethod also amplifies noise compositions and thus lowers photometrycapability.

Concerning the above problem, the camera 10 of the present embodimentuses the extra aperture size when the brightness is low so that anamount of light to the solid-state imaging device 28 increases. Thus,the noise compositions can be suppressed and at the same time thephotometry capability under low brightness can be improved.

FIG. 9 shows a relationship between the view angle at taking and adivided photometry detect area of AE. FIG. 9 shows an example in whichthe screen is divided into sixteen areas (4×4=16), but manners ofdividing are not limited; for example, the area can be divided into 256areas (16×16=256). If a method for the photometry of AE measures anaverage brightness of each of the divided photometry detect areas 64, acalculation for photometry is not affected by that despite thatdeterioration of the image quality such as blur occurs at the peripheryof the screen, because the signals are averaged.

Therefore, light in an amount that is four times as the normal takingcan be provided and at the same time the capability at the lowbrightness side can be improved by four times, by performing the AEprocess with the aperture size (e.g. F1.4) which provides morebrightness than the aperture size (F2.8) which is used for the viewangle 60 at taking.

FIG. 10 shows a control flowchart for executing the method. When thecamera control starts (Step S200) and the AE process starts byhalf-pressing the release switch 18, the photometry for subjectbrightness for measuring the brightness of the subject is performed(Step S210). The subject brightness obtained by the photometry and thespecified value are compared, and whether or not the brightness is at ameasurable level is determined (Step S212).

If the subject brightness is determined to be extremely dark and the AEphotometry cannot be performed normally with the normal aperture sizedue to small outputs of the solid-state imaging device 28, the processgoes on to Step S214. At Step S214, the extra aperture size of F1.4 isselected which is an aperture size at outside the normal diaphragmoperation range, and the photometry is performed again with the aperturesize.

The process afterwards goes on to Step S218, and an aperture size at atime of taking and a shutter speed are calculated from a photometryvalue obtained by the last photometry and a program line, and theaperture size is set in accordance with a result of the calculation. Atthat time, the iris within the normal iris operation range (F2.8-F8) isselected. The image is darker with the aperture size at taking than theimage with the aperture size at the photometry (extra aperture size).However, if the subject brightness is determined to be a level at whichthe subject brightness can be measured at Step S212, the process goes onto Step S218, the iris for a normal taking (taking for recording) iscalculated from the photometry value obtained at the subject brightnessphotometry and the predetermined program line, and the iris is set inaccordance with the result of the calculation.

After that, the exposure operation is performed (Step S220) afterpressing the release switch 18, and the image data obtained at theexposure operation is stored in the external storage device after goingthrough the required signal processes (Step S222), then the controlsequence is completed (Step S224).

When using the extra aperture size, lowering of the amount of light atthe periphery of the screen may occur in addition to the blurringphenomenon. Concerning the phenomena, the data showing a trend oflowering of the amount of light at the periphery is preferably stored inthe ROM and the like, and correction is performed by using the data at atime of the AE with the extra aperture size.

Embodiment 3 Extra Aperture Size at a Time of the Electronic Zoom

An electronic camera has an electronic zoom function (also called adigital zoom function) which enlarges only the center of the screen byan electronic process and takes the expanded image. When the enlargingprocess is performed by the electronic zoom function, vibrations easilyoccur due to a pseudo focal length which is long.

In general, a limit of the shutter speed without vibrations is 1/(focallength: millimeter). For example, the limit of the shutter speed withoutvibrations is 1/100 seconds if the focal length is 100 mm. When theelectronic zoom magnification is twice, the focal length is two timeslong, so the focal length is 200 mm with the camera with the focallength 100 mm. The limit of the shutter speed without vibrations is1/200 seconds, which means the vibrations more easily occur.

As described in reference to FIG. 5, the camera 10 of the presentembodiment concerns that only the center of the screen is a taking areaat a time of the electronic zoom, and is thus controlled to increase theamount of light to the solid-state imaging device 28 by using the extraaperture size. Therefore, the shutter speed can be accelerated while thevibrations can be eliminated.

FIG. 11 shows a relationship between the view angle at a time of normaltaking and the view angle at a time of the electronic zoom. In contrastto the view angle 60 at a time of normal taking which does not use theelectronic zoom, the image quality can be secured in the area 66 whenusing an electronic zoom A since the electronic zoom A uses only thearea 66 which is one quarter of the center of the screen. Therefore, theamount of light to the solid-state imaging device 28 can be increased byfour times by setting a brighter iris (e.g. F1.4) than the iris withF2.8 which is used for the view angle 60 at a time of normal taking,hence the resulting shutter speed can be four times fast.

In a case of an electronic zoom B, an area indicated by a referencenumber 68 is a view angle at taking. Since the taking area 68 of theelectronic zoom B is larger than that of the electronic zoom A, theimage quality may not be secured with respect to the area that is a halfof the center of the screen (an outer peripheral portion of the area 66of the electronic zoom A) if setting the iris at F1.4. Concerningsecuring the image quality, the camera is controlled to use the iris atabout F2.0 when using the electronic zoom B. Therefore, an accurate AFcontrol is possible by changing the iris being used at the aperture sidecorresponding with a magnification of the electronic zoom.

FIG. 12 shows a control flowchart for executing the process. When thecamera control starts (Step S300) and the release switch 18 ishalf-pressed, ON/OFF of the electronic zoom is confirmed (Step S310),then whether or not the electronic zoom is used is determined (StepS312). If the setting of the electronic zoom is ON, the step goes on toStep S314, and the extra aperture size (e.g. F1.4) is set correspondingwith the magnification of the electronic zoom, and an iris at the timeof taking and the shutter speed are calculated by following the programline for using the extra aperture size (F1.4) to F8, and the iris is setin accordance with a result of calculation.

On the other hand, if the setting of the electronic zoom is OFF at StepS312, the step goes on to Step S316, and the program line for using thenormal iris operation range (in this case F2.8-8) is used.

Next, when the release switch 18 is fully pressed, the exposureoperation is performed (Step S320), and the image data obtained at thattime is stored (Step S322) in the external storage device after goingthrough the required signal processes, and the control sequence iscompleted (Step S324).

Embodiment 4 Extra Aperture Size for the Moving Image

A real time image (moving image) during taking is displayed in theelectronic still camera in order to confirm a view angle. The imagingpixels have been improved, so the pixels are thinned out and displayed.In this case, as described with reference to FIG. 6, required opticalcapability (e.g. MTF) of the lens differs at the time of taking forrecording a moving image and photographing a still image. In otherwords, superior optical capability is required at the time of recordinga still image, but deterioration of the moving image when displayed isnot concerned a lot even though the optical capability of the lens isdecreased, because pixels are thinned out.

At a time of a normal taking for recording the still image, a brightimage can be obtained by a flashing device which emits light insynchronism with exposure; but at a time of taking for recording themoving image, the taken image is dark under low brightness and the imagecannot be confirmed because the output from the solid-state imagingdevice is lowered.

In order to cope with the above problem, the conventional art increasedthe output gain from the imaging device and amplified the signal inorder to display the image under low brightness as a bright image.However, if the imaging signal is amplified, the noise composition isamplified and the image quality of the moving image is deteriorated.

Thus, the camera 10 of the present embodiment uses an extra aperturesize with respect to the subject under low brightness at a time oftaking the moving image so as to increase the amount of light to thesolid-state imaging device 28; whereby the noise compositions aresuppressed and at the same time the display for confirming the viewangle under low brightness can be viewed to a section closer to the lowbrightness side.

FIG. 13 shows the control flowchart for executing the process. When thecamera control starts (Step S400), whether the current operation is fortaking a moving image or for a normal taking (Step S410). If the currentoperation is for taking a moving image, a program line in the iris rangeincluding the extra aperture size (e.g. F1.4) is used (Step S412) sincea bright iris which lowers the optical capability but does not affectthe displayed image can be used.

On the other hand, if the current operation at Step S410 is for thenormal taking, a program line is used for deciding an exposure in anormal iris range (F2.8-F8) which secures the predetermined opticalcapability (Step S414). Then, the exposure is performed (Step S416) byan iris and a shutter speed which are obtained in accordance with thepredetermined program line at Step S412 or at Step S414.

Embodiment 5 Extra Aperture Size in a Low Resolution Mode

Since imaging pixels have been improved, an electronic still camera mayhave a high resolution mode for recording all the pixels withoutthinning out and a low resolution mode for recording after thinning outin order to reduce a size of an image file.

In that case, required optical capability of the lens differs in thehigh resolution mode and the low resolution mode. When taking by thehigh resolution mode, superior optical capability is required to thelens in order to obtain a high quality image by using the data of allthe pixels; however, when taking by the low resolution mode,deterioration of the taken image quality may not be concerned a lotdespite that the optical capability of the lens is lowered, because thepixels are thinned out.

Therefore, the camera 10 of the present embodiment is controlled to usethe extra aperture size with respect to the subject under low brightnessin the low resolution mode so as to increase the amount of light to thesolid-state imaging device 28. Thereby the frequency of use of thestrobe device is decreased and an image with a small amount of strobelight can be taken with an optimum exposure; moreover, electricityconsumption of a power source battery can be decreased by the control.

FIG. 14 shows the control flowchart for executing the process. When thecamera control starts (Step S500) and the release switch 18 ishalf-pressed, whether or not the current taking mode is set at the lowresolution mode is determined (Step S510). If the current taking mode isset at the low resolution mode, a program line for deciding exposure inthe focus range which includes the extra aperture size (e.g. F1.4) (StepS514) since an aperture size for providing more brightness is used whichlowers the optical capability of the lens but does not affect the takenimage.

Next, when the release switch 18 is fully pressed, the exposureoperation is performed (Step S520) by an aperture size and a shutterspeed which are obtained in accordance with a predetermined program lineat Step S512 or Step S514. The image data obtained by the exposure isstored in the external storage device 48 after going through therequired signal processes (Step S522), and the control sequence iscompleted (Step S524).

In a case where the low resolution mode is provided in plural levelscorresponding with a thinning out rate, an area which allowsdeterioration of the image changes corresponding with the thinning outrate; thus the value of the extra aperture size is preferably changedcorresponding with the thinning out rate.

Embodiment 6 Extra Aperture Size for the Moving Image

The electronic still camera may display a moving image in purpose ofconfirming the image. The moving image is displayed by thinning out thepixels since the imaging pixels have been improved. In that case, therequired optical capability of the lens differs for taking a movingimage and a normal taking. In other words, deterioration of thedisplayed image may not be concerned a lot if the optical capability islowered to some extent.

Moreover, if the subject under extreme brightness such as the sun or alight, a smear phenomenon is known to occur in which bright lines appearfrom the bottom to the top of the image of the subject under extremebrightness. If the smear occurs in a moving image for confirming theview angle, not only the quality of the image but also the observabilityof the displayed image is lowered. Although the smear can be eliminatedby closing a mechanical shutter at a high speed in the normal taking,the mechanical shutter cannot be closed while taking a moving image.

In order to cope with this problem, the camera 10 of the presentembodiment is provided with a focus position with an aperture of a sizewhich is not used for the normal taking (hereunder called “an extrasmall size” which means the minimum focus position at outside thespecified range). When taking a moving image, the extra small size isused so as to decrease the smear and at the same time the amount oflight entering into the solid-state imaging device 28 is decreased, inorder to improve the quality as well as observability of the movingimage.

FIG. 15 shows the control flowchart for executing the process. When thecamera control starts (Step S600), whether the current operation is fortaking the moving image or for the normal taking is determined (StepS610). If the current operation mode is for taking a moving image, aprogram line in the focus range including the extra aperture size (e.g.F11) is used (Step S612) since an aperture size can be used which lowersthe optical capability but does not affect the displayed image.

On the other hand, if the current operation at Step S610 is for thenormal taking, a program line is used for deciding an exposure in anormal focus range (F2.8-F8) which secures the predetermined opticalcapability (Step S614). Then, the exposure is performed (Step S616) byan aperture size and a shutter speed which are obtained in accordancewith the predetermined program line at Step S612 or at Step S614.

In the embodiment, the iris diaphragm 26 is used as the diaphragmmechanism; but the diaphragm mechanism is not limited to the irisdiaphragm 26 for achieving the present invention. Another diaphragmmechanism may also be used in which a predetermined aperture size isselected by rotating a turret plate having plural holes.

Now, alternative embodiments will hereunder be described for improvingthe capability of the camera by focusing on elements other than thediaphragm.

Alternative Embodiment 1

FIGS. 16 and 17 are views showing an outer appearance of a camera 70 andFIG. 18 is a block diagram of the camera 70 in the alternativeembodiments of the present invention. The parts which are similar or thesame as those of the camera 10 are assigned the same reference numbers,and the description on them is omitted.

A wide conversion lens 72 can be attached to the top end of the barrelof the camera 70 in FIG. 16. Moreover, the camera 70 has the mode dial13, and the photometry sensor 15 comprising an AF illuminating part 15Aand an AF light receiving part 15B is disposed at the front face of thecamera. An active sensor is used in the present embodiment, but thephotometry sensor is not limited to that; sensors such as a phasecontrast sensor of a passive format may be used.

The mode dial 13 is a means for selecting operation modes of the camera.Modes such as a set up mode, a successive taking mode, a manual takingmode, an automatic taking mode, a scene selecting mode, and a movie(moving image) taking mode, a reproducing mode, can be set by operatingthe mode dial 13. Marks indicating each of the modes are printed on thetop of the mode dial 32 (the marks are a pictorial character or a symbolillustrating the modes). A mode is set by matching a mark of a desiredmode with a predetermined position.

When the set up mode is selected, a set up screen is displayed on theliquid crystal monitor 22. In the set up screen, a desired combinationcan be selected among plural image sizes (pixels) and plural compressionrates (qualities) which are prepared beforehand. Specifically, regardingthe image size (a number of pixels), there are 2832×2128 pixels,2048×1536 pixels, 1280×960 pixels, 1280×960 pixels, or 640×480 pixelsare selectable image sizes. Regarding the compression rate, “FINE” whichis ¼ (JPEG) compression, “NORMAL” which is ⅛ (JPEG) compression, “BASIC”which is 1/16 (JPEG) compression are selectable qualities. A userdesignates a combination of the image size and the compression ratewhich are suitable for a purpose of the taking. In a movie (movingimage) mode, the image size, the frame rate, and the recording methodare predetermined; for example, moving image data should be recorded by320×240 pixels, 10 frames per seconds, and Motion JPEG format whentaking a moving image.

In a scene selecting mode, a portrait mode, a scene mode, a night viewmode, and a monochrome mode can be set by operating a menu. A settingsuitable for a scene to be taken is automatically done by using thosemodes corresponding with taking conditions.

As seen from FIG. 17, a cross key 21 is provided to the rear face of thecamera 70. The cross key 21 is a multi-function button which can inputinstructions of the four directions: up and down, and right and left.The cross key 21 is used as an operation button for instructingselecting of the respective setting items and a change of settingcontents in the menu screen, and at the same time is used as aninstruction means for magnification adjustment operation (zoomoperation) and for forwarding and rewinding the reproduced frame.

As seen from FIG. 18, the sensor 74 for detecting attachment of the wideconversion lens 72 is provided at the top end of the optical unit withwhich the wide conversion lens 72 is detachable, and the detected signalof the sensor 74 is transmitted to the control CPU 32 via a conversiondetecting circuit 75. The CPU 32 can recognize the attachment of thewide conversion lens 72 by the detected signal notified from theconversion detecting circuit 75.

A photometry sensor control circuit 77 controls operations of thephotometry sensor 15 in accordance with an instruction from the CPU 32.The detected signal obtained from the photometry sensor 15 istransmitted to the CPU 32 via the photometry sensor control circuit 77.The CPU 32 can recognize the focal length by the detected signal fromthe photometry sensor 15.

A strobe control circuit 78 controls the flash of the strobe emittingpart 14 in accordance with the CPU 32. In other words, the strobecontrol circuit 78 controls charging of a main condenser (not shown) aswell as a timing for emitting light to the strobe emitting part 14, andalso controls stopping the light emission based on the detected resultof a strobe light adjusting sensor. The subject under low brightness canbe taken at a proper exposure level by emitting light from the strobeemitting part 14.

As described before, the iris diaphragm 26 can be changed in the rangeF1.4-F11, but the range F2.8-F8 secures the predetermined opticalcapability. In general, the image quality at the periphery of the screenis lowered and the image is blurred when the diaphragm is opened toolarge. Since the image should not be taken by the diaphragm, the imageis usually taken in accordance with a program line which uses F2.8-F8,which satisfied the optical capability.

Despite the fact that the image quality at the periphery of the screenis lowered when the diaphragm is opened, the image quality at the centerof the screen is hardly affected. In a case where the strobe emits lightunder low brightness, a reaching length of the strobe light can beextended by changing the control of the diaphragm at the aperture sidebecause the main subject is often present at the center of the screeneven though the image quality of the periphery is lowered.

The reaching length L of the strobe light is determined by an amount oflight G No emitted from the strobe and a focus value F of the camera,and is defined by the following formula (1)G No=F×L  (1)

Since G No is constant in cameras, the smaller the F is (that is, thediaphragm is opened), the longer the reaching length L will be.Therefore, the reaching length can be extended by using the apertureside rather than the side which is used for the normal taking (strobeunused).

Yet, the image is easily deteriorated if the aperture side is alwaysused; thus the taking is executed by the focus within the range whichsecures the capability as far as the focus (F value) can secure thecapability by the outputs of the photometry sensor 15 which arecalculated from the formula (1). If the focal length to the subject islonger, the focus is used with which the image quality at the peripheryof the image is not in the range that secures the capability, in orderto avoid deterioration of the capability.

As shown in FIG. 9, the strobe emits light (pre-emission), and dividingphotometry is performed by using the photometry means of the AE/AFdetect block 38. In FIG. 18, a view angle 30 is divided into small 64(8×8) blocks like a matrix, and the 16 (4×4) blocks at the center of thescreen are set as a central photometry area 81, and other blocks are setas a peripheral photometry area 82.

If a photometry value at the central photometry area 81 is high and aphotometry value of the peripheral photometry area 82 is low (that is,the periphery is dark) as a result of the dividing photometry, it isrecognized that the subject is not present at the periphery of thescreen. In that case, the extra aperture size may be used in combinationof the result of the photometry by giving a condition that the subjectdistance is long and the subject is not present at the periphery of thescreen after the pre-emission.

Assuming that the wide conversion lens is attached to the camera, theimage quality at the periphery tends to be poor, but as describedbefore, such deterioration of the image quality at the periphery may beaccepted. Since the lighting characteristics of the strobe device builtin the camera is inherently designed to correspond with the view anglewhen the wide conversion lens is not used (when a standard taking lensis used), the strobe is not emitted to the periphery in the view angleat taking with the wide conversion lens being attached (which means thestrobe does not reach to the periphery of the view angle at taking).Therefore, the camera 70 of the present invention can extend a reachingdistance of the strobe by using the extra aperture size in a case wherea taking is performed in accompaniment with the strobe emission.Moreover, whether or not the extra aperture size is used may bedetermined in combination with the photometry result by the photometrysensor 15.

Alternative Embodiment 2

Next, another alternative embodiment of the present invention will bedescribed. FIG. 20 is a block diagram of a camera 90 of the presentembodiment. The same or similar parts as those in FIG. 3 are assignedthe same reference numbers and the description on them is omitted.

A taking system (the taking lens 12) of the camera 90 in FIG. 20 has azoom lens 91 and a focus lens 92. A lens group 91A and a lens group 91Bmove along an optical axis while a positional relationship between thetwo lens groups 91A and 91B is regulated by the cam mechanism (notshown) in order to change a focal length. A zoom control circuit 94controls driving of the zoom lens 91 in accordance with an instructionfrom the control CPU 32. The focus lens 92 contributes to focusadjustment. A focus control circuit 95 controls driving of the focuslens 92 in accordance with an instruction from the CPU 32.

A signal from the operation part such as the release switch 18 and thecross key 21 is inputted into the CPU 32 via an input key controlcircuit 96. The CPU 32 processes and controls properly based on anoperation signal received from the input key control circuit 96, plusthe CPU 32 also obtains the focal length data and focus position datavia the zoom control circuit 94 and the focus control circuit 95 andcontrols the diaphragm control circuit 30, the zoom control circuit 94,and the focus control circuit 95 based on the obtained data. Anon-volatile memory 97 composed of an EEPROM and a flash ROM stores datarelated to the MTF of the taking lens 12 installed in the camera 90. TheCPU 32 refers the data within the non-volatile memory 97 as required,and performs corrections in accordance with an aperture size of thediaphragm, a focus position, and a zoom position.

In general, macro capability of the camera is regulated by the imagequality of the lens in many cases, and a short distance limit (MOD) isset by referring to the MTF at the center or the periphery of thescreen. When taking under a low resolution mode, however, the takenimage is not affected despite some deterioration of the MTF at thecenter of the screen because a resolution mode at the time of the takingis the low resolution mode. The taken image is not affected either ifthe image quality of the central portion (area to be recorded) issecured despite the poor resolution capability at the periphery in acase of taking by using an electronic zoom (a function for enlarging animage by a signal process rather than by an image processing technologyfor electronically processing the taken image data so as to enlarge theimage).

Therefore, a taking in a subject distance which is shorter than theshort distance limit (MOD) in the normal taking can be performed at atime of taking under the low resolution mode or taking by using theelectronic zoom.

FIGS. 21 and 22 shows a relationship between the subject distance andthe lens capability. FIG. 21 is a graph indicating a relationshipbetween the focus position and the MTF (in a case of a taking under alow resolution). A solid line indicates the MTF which is at the centerof the view angle when taking, and the dotted line indicates the MTF atthe periphery.

As seen from FIG. 21, a restriction (short distance limit) at the shortdistance side in the normal taking is designated since 35% or more areaof the MTF both at the center and the periphery in the normal taking isdetermined as a level to secure the image quality. Thus the focusadjusting range in the normal taking is regulated as shown in (1).

In the low resolution, however, the taken image is not affected despitethe MTF being lowered down to 20%, so a taking in still a shorterdistance can be possible in the low resolution mode. Therefore, thecamera 90 of the present embodiment changes the focus adjusting range(regulation at the short distance side) corresponding with theresolution when taking which is determined by a combination of the imagesize (pixel) and the compression rate (quality), and expands the focusadjusting range closer to the short distance side as shown in (2).

FIG. 22 shows the relationship between the focus position and the MTF.As seen from FIG. 22, the area in which the MTF at the center and theperiphery of the screen in the normal taking is 35% is a level that cansecure the image quality. However, because it is satisfactory to secure35% or more at the center only in the electronic zoom, a taking in stilla shorter distance is possible in a range which satisfies the 35% level.Thus, the camera 90 of the present embodiment changes the focusadjusting range corresponding with a magnification of the electroniczoom, and controls to make the taking possible at a side still closer tothe short distance side as shown in (3).

Alternative Embodiment 3

FIGS. 21 and 22 show an embodiment for use at outside the range whichsecures the capability with respect to the focus position (focus), butthere is also am embodiment for use at outside the range which securesthe capability with respect to the focal length (zoom). FIGS. 23 and 24show the relationship between the focal length and the lens capability.

FIG. 23 shows a graph of a relationship between the focal length and theMTF (when taking under low resolution). As seen from FIG. 23, an areawhere the MTF at the center and the periphery is 35% or more in thenormal taking is the level which secures the capability, by which theregulation at a telephoto side is decided; in short, a focal lengthchangeable range (zoom range) in the normal taking is regulated as shownin (4).

In the low resolution, however, the taken image is not affected despitethe MTF being lowered down to 20%, so the taking at a side which isstill closer to the telephoto side is possible in the low resolutionmode. The camera 90 in the present embodiment changes the zoom range(regulation at the telephoto side) corresponding with the resolution attaking which is determined by a combination of the image size (pixel)and the compression rate (quality), and expands the focus adjustingrange closer to the short distance side as shown in (5).

FIG. 24 shows the relationship between the focus position and the MTF.As seen from FIG. 22, the area in which the MTF at the center and theperiphery of the screen in the normal taking is 35% is a level that cansecure the image quality. However, because it is satisfactory to secure35% or more at the center only in the electronic zoom (digital zoom), ataking of a side which is closer to the telephoto side is possible in arange which satisfies the 35% level. Thus, the camera 90 of the presentembodiment changes the focus adjusting range corresponding with amagnification of the electronic zoom, and controls to make the takingpossible of a side which is still closer to the telephoto side as shownin (6).

FIG. 25 is a schematic view of the zoom range by a zoom control, whichis a combination of the optical zoom and the electronic zoom. As seenfrom FIG. 25, only the center portion of the view angle at taking isenlarged by the electronic zoom after driving the zoom from a widephotoend of the optical zoom to the end position (first telephoto side) at along focal length side which can be taken in the normal taking. The zoomrange of the optical zoom (limit position of the telephoto side) isextended by following the enlarging process of the electronic zoom, thusthe zoom can be driven by the optical zoom to a second telephoto end ata long focal length side after extending the zoom range of theelectronic zoom up to the limit (the telephoto end of the electroniczoom).

Alternative Embodiment 4

Vibrations occur more easily when the focal length of the taking opticalsystem is closer to the telephoto side, but blur caused by suchvibrations may not be very obvious in a taking under low resolution.Thus, an amount of blur (amount of vibrations) of the image iscalculated and the amount of blur and the image quality data arecompared. If the amount of the blur by the vibration is more than theeffects of deterioration of the image quality, the extra aperture sizeis used so as to accelerate the shutter speed, and an image is takenpreferably at a point at which the vibrations and the image quality arebalanced. In addition, a known detecting means such as an angle speedsensor may be applied to the method for detecting the vibrations.

Alternative Embodiment 5

In order to achieve a taking at outside the range which secures thecapability of the taking optical system, the resolution of the takenimage can be improved by changing an edge (contour) intensity process(so-called an “aperture process”) with respect to the image signal. Inother words, resolution is improved by intensifying the contour in theaperture process so that the lowered image quality when using at outsidethe range which secures the capability is supplemented. The resolutionof the outputted image can be equal within the range which secures thecapability despite a change in MTF by changing the aperture processcorresponding with the aperture size of the diaphragm.

The aperture process (contour correction process) is performed in thesignal processing part 42 in FIG. 20. FIG. 26 is a block diagram showingan example of a structure of the contour correcting circuit. A contourcorrection circuit 100 in FIG. 20 comprises a contour signal producingcircuit 110, a multiplier 112 which multiplies a contour signal by again, a coring circuit 114 which reduces values of a small amplitudecomponent of an output of the multiplier 112 to zero, and an adder 116for adding a contour correction signal outputted from the coring circuit114 to original brightness signal.

A gain value a of the multiplier 112 and a coring level in the coringcircuit 114 are controlled by the CPU 32 in FIG. 20. The CPU 32 changesthe gain value α and the coring level so as to supplement the loweredimage quality when used at outside the range which secures thecapability by referring to the data within the non-volatile memory 97.Thereby, correction of every diaphragm and correction by the focusposition or the zoom position can be achieved.

Alternative Embodiment 6

FIG. 27 is a section view of a solid-state imaging device (CCD) 120 ofthe present embodiment. As seen from FIG. 27, the CCD 120 has astructure in which many photodiodes 122 are arranged in serial on aplane. A micro lens 124, which forms the subject image on the lightreceiving surface of each of the photodiodes, is provided so as tocorrespond with each of the photodiodes 120.

As seen from FIG. 27, a light shielding mask 126 is provided between themicro lens 124 and the photodiodes 122 in order to adjust the aperturewith respect to the micro lens 124 positioned at a periphery A in theCCD light receiving surface. On the other hand, the light shielding maskis not provided to a section of a central portion B in the CCD lightreceiving surface.

Since the CCD 120 in the structure described above adjusts the amount oflight entering into the photodiodes 122 of the periphery A,deterioration of the image quality at the periphery can be preventedcompared with a conventional CCD without the light shielding mask 126.In other words, the CCD 120 adjusts the aperture of the micro lens withthe light shielding mask 126 in the area in which the conventional CCDcannot be used due to the deteriorated image quality at the periphery,thus the CCD 120 can be used at outside the area which secures thecapability.

If the CCD 120 in the structure described above and shown in FIG. 27 isused, the amount of light at the periphery decreases, and shading(difference in brightness in an image) increased; but this problem canbe resolved by performing a known shading correction process in thesignal processing part 42 in FIG. 20.

In FIG. 27, the periphery A is provided with the light shielding mask126 while the periphery B is not; but sections are not restricted todivide the sections in two, but plural types of aperture rate of thelight shielding mask may be set, and the aperture rate decreases fromthe center to the periphery of the screen.

Alternative Embodiment 7

Sometimes an image which suites a mode better if blurred at theperiphery, depending on some taking modes selected by the camera 90. Forexample, a portrait mode is one which fits this situation, in which thesubject at the center of the screen appears clearly with respect to theblurred periphery. In that case, the aperture size of the diaphragm isset at the aperture side in order to narrow the depth of field; but theblur at the periphery increases regarding the focus at outside the rangewhich secures the capability if there is a focus area in which only theimage quality at the periphery is deteriorated. Thus the focus area (thearea at outside the range which secures the capability) can be used.

FIG. 24 shows the relationship between the focus position and the MTF.When the portrait mode is selected by the mode dial 13 in FIG. 16, thecamera is automatically controlled so that the image which is blurred atthe periphery is taken by using the program line that uses the extraaperture size. Taking modes which can be selected by the mode dial 13are a sport mode which is suitable for taking a moving subject (a modewhich takes priority to the shutter for taking an image at a shutterspeed at a high speed side), a night view mode, a scenery mode, and soforth. The night view can be taken bright by using the extra aperturesize, and the extra aperture can also be used at a time of a slowsynchronism using a strobe (a strobe taking by a slow shutter whichtakes the night view and the subject with a good quality).

As described above, the present invention provides unspecified aperturesizes (extra aperture size and extra small size) which are not used fora normal taking, and uses the unspecified aperture sizes correspondingwith an operating situations such as automatic exposure, auto focus,eletronic zoom, movie display, and taking after thinning out (under alow resolution mode). Therefore, the capability lens can be fullyapplied without deteriorating the taken image, and the respectivecapability of the camera can be improved.

Moreover, the present invention provides a technique for improving andexpanding the capability of the camera by providing a wider interlockingrange than a normal taking range, with regard not only to the diaphragmbut also to zoom range (operatable range of a focal length) and a focusadjustable range, and using the lens at outside the range which securesits capability corresponding with a taking condition and a special use.

It should be understood, however, that there is no intention to limitthe invention to the specific forms disclosed, but on the contrary, theinvention is to cover all modifications, alternate construction andequivalents falling within the spirit and scope of the invention asexpressed in the appended claims.

1. An apparatus for controlling an aperture of a camera, comprising: afirst determining device that determines an aperture range for a normalshooting which secures predetermined optical capability; a seconddetermining device that determines an aperture range including anaperture out of the aperture range for the normal shooting; and acontrolling device that controls a diaphragm mechanism to set anaperture within the aperture range determined by said second determiningdevice for a shooting with electronic zoom, and controls the diaphragmmechanism to set an aperture within the aperture range determined bysaid first determining device for a shooting without the electroniczoom, wherein a first program line determines an aperture for taking,the size of the aperture being in a first aperture range defined in arange from a first aperture value to a second aperture value, whereinthe aperture is used when shooting without the electronic zoom, and asecond program line determines another aperture for taking, the size ofsaid another aperture being in a second aperture range including a thirdaperture value smaller than said first aperture value, wherein saidanother aperture is used when shooting with the electronic zoom.
 2. Acamera, comprising: a taking lens; a diaphragm mechanism that adjusts anamount of light which enters the camera through said taking lens; animaging device that converts the light, entering the camera though saidtaking lens and said diaphragm mechanism, into electric signals; anelectronic zoom processing device that produces an enlarged image of apartial area corresponding with the center of a screen by using signalsof the area corresponding with the center of the screen among imagesignals outputted from said imaging device; an operating device forselecting presence of using said electronic zoom processing device; astorage device for storing image data obtained through said imagingdevice in a storage medium; a first determining device that determinesan aperture range for a normal shooting which secures predeterminedoptical capability; a second determining device that determines anaperture range including an aperture out of the aperture range for thenormal shooting; and a controlling device that controls the diaphragmmechanism to set an aperture within the aperture range determined bysaid second determining device for a shooting with the electronic zoomprocessing device, and controls the diaphragm mechanism to set anaperture within the aperture range determined by said first determiningdevice for a shooting without the electronic zoom processing device,wherein a first program line determines an aperture for taking, the sizeof the aperture being in a first aperture range defined in a range froma first aperture value to a second aperture value, wherein the apertureis used when shooting without the electronic zoom, and a second programline determines another aperture for taking, the size of said anotheraperture being in a second aperture range including a third aperturevalue smaller than said first aperture value, wherein said anotheraperture is used when shooting with the electronic zoom.